The development of zooarchaeology in Eastern North America can be broken up into three different periods. The first being the Formative period starting around the 1860s, the second being the Systematization period beginning in the early 1950s, and the Integration period which began about 1969.
Full-time zooarchaeologists didn't come about until the Systematization period. Before that it was just a technique that was applied but not specifically studied.
Zooarchaeological specialists started to come about partly because of a new approach to archaeology known as processual archaeology. This approach puts more emphasis on explaining why things happened, not just what happened. Archaeologists began to specialize in zooarchaeology, and their numbers increased from there on.